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This article is about the networking term. For other uses, see Black hole (disambiguation).

In networking, black holes refer to places in the network where incoming traffic is silently discarded (or "dropped"), without informing the source that the data did not reach its intended recipient. Computer networking is the Engineering Discipline concerned with communication between Computer systems or devices Networking routers Internet traffic is the flow of Data around the Internet. It includes Web traffic, which is the amount of that data that is related to the World Wide

When examining the topology of the network, the black holes themselves are invisible, and can only be detected by monitoring the lost traffic; hence the name. Network topology is the study of the arrangement or mapping of the elements ( links, nodes, etc

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Dead addresses

The most common form of black hole is simply an IP address that specifies a host machine that isn't running or an address to which no host has been assigned. An Internet Protocol ( IP) address is a numerical identification ( Logical address) that is assigned to devices participating in a Computer network

Even though TCP/IP provides means of communicating the delivery failure back to the sender via ICMP, traffic destined for such addresses is often just dropped. The Internet Protocol Suite (commonly TCP/IP) is the set of Communications protocols used for the Internet and other similar networks The Internet Control Message Protocol ( ICMP) is one of the core protocols of the Internet Protocol Suite.

Firewalls and "stealth" ports

Most firewalls can be configured to silently discard packets addressed to forbidden hosts or ports, resulting in small or large "black holes" in the network. A firewall is an integrated collection of security measures designed to prevent unauthorized electronic access to a networked computer system In Information technology, a packet is a formatted unit of Data carried by a Packet mode Computer network.

Black hole filtering

Black hole filtering refers specifically to dropping packets at the routing level, usually using a routing protocol to implement the filtering on several routers at once, often dynamically to respond quickly to distributed denial-of-service attacks. A routing protocol is a protocol that specifies how Routers communicate with each other to disseminate information that allows them to select routes between any two A router ('rautər in the USA 'rutər in the UK and Ireland, or either pronunciation in Australia and Canada is a Computer whose software and hardware are usually

PMTUD black holes

Main article: Path MTU discovery#Problems with PMTUD

Some firewalls incorrectly discard all ICMP packets, including the ones needed for Path MTU discovery to work correctly. Path MTU discovery ( PMTUD) is a technique in Computing for determining the Maximum transmission unit (MTU size on the network path between two IP hosts Path MTU discovery ( PMTUD) is a technique in Computing for determining the Maximum transmission unit (MTU size on the network path between two IP hosts This causes TCP connections from/to hosts with a lower MTU to hang. In Computer networking, the term Maximum Transmission Unit ( MTU) refers to the size (in Bytes of the largest packet or frame

See also

External links

In Unix-like Operating systems /dev/null or the null device is a Special file that discards all data written to it (but reports that Internet background noise (IBN consists of data packets on the Internet which are addressed to IP addresses or ports where there is no network In Computer networking, a packet drop attack or blackhole attack is a type of Denial-of-service attack accomplished by dropping packets The attack
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